1. Field of the Invention
The present invention relates to an improvement in low-pressure casting techniques both in shell and in sand molds.
2. Brief Description of the Prior Art
It is known that large-area pieces of heterogeneous constitution can be cast by pouring through multiple gates leading from a distribution chamber, which may be heated, being situated below the mold cavity. This arrangement is mainly reserved for uncored pieces or for those the cores of which expose little surface area outside the castings. Such an arrangement is described in the French Pat. No. 2,287,294 in the name of the present applicant.
However, for the casting of heavily cored pieces in shells, where a large quantity of sand is present around the castings, as well as in the case of pieces cast in molds entirely of sand, it is desirable to avoid this arrangemment, since grains of sand can fall into the distribution chamber through the gates. The result is inclusions which lower the quality of the castings.